Abstract/Project Summary Applicant: Dr. Wang holds M.D. and Ph.D. degrees, and has completed specialized training in both neurology and epilepsy. During his Ph.D. work, he published 9 manuscripts including three first-author papers in Neuroscience and one second-author paper in Nature Medicine. During his neurology training, he conducted a genetic study on familial paroxysmal kinesigenic dyskinesia and co-authored one paper (under review). Research Plan: Defining how genetic mutations that cause infantile epileptic encephalopthies (IEEs) disrupt neurodevelopment should provide conceptual insights broadly relevant to understanding brain development and epilepsy mechanisms. Using CRISPR genome editing methods, in utero electroporation (IUE) and human induced pluripotent stem cell (iPSC) cultures, I propose to study the function of SPTAN1, a recently identified gene (encoding alpha II-spectrin) mutated in patients presenting with IEE. My preliminary data show that SPTAN1 regulates critical aspects of neuronal development, including axonal initial segment (AIS) formation, process outgrowth and clustering of postsynaptic proteins. My central hypotheses are that SPTAN1 plays critical roles in neurodevelopment through regulating neuronal migration, process outgrowth and synapse formation, and that disinhibition of excitatory neurons leads to seizures in SPTAN1 IEE. I propose two specific aims to test my hypotheses: 1) To determine how deleting Sptan1 or overexpressing mutant SPTAN1 in cortical pyramidal neurons alters brain development and network excitability; and 2) To establish how mutations in SPTAN1 influence excitatory and inhibitory cortical neuron development and excitability using patient-derived iPSCs. This innovative proposal combines a rat IUE in vivo model (Aim 1) and an in vitro model with patient-derived neurons (Aim 2). These models will be invaluable tools to study brain development, and will also serve as an entry point for future drug screening using patient-derived neurons. Immediate and long-term career goals: My career goal is to become an independent physician-scientist focusing on brain development and genetic epilepsies. My long-term goal is to understand how genetic mutations alter neurodevelopment and ultimately lead to seizures and intellectual disability. My short-term goal is to obtain knowledge (e.g., stem cell biology and electrophysiology) and skills (e.g., iPSC cultures, viral- based gene manipulation) in neuroscience to fill the gaps of my previous training in order to augment my chances of success as an independently funded neuroscientist. The key elements of this research career development plan are 5 key training goals. They are stem cell biology, electrophysiology principles, viral vector based genetic manipulation, grant writing and laboratory management skills.